Quantitative delta' phase analysis in Al-Li alloys using the Rietveld method

Powder X-ray diffraction and the Rietveld method have been exploited to determine quantitatively the mass fraction and the mean size evolution with aging time of the delta' precipitates in an Al-Li alloy at 453 K. Although obtaining good refinements is not straightforward, the principal difficulties being the texture of the sample, the small intensities of the delta' peaks, the coincidence of the most intensive delta' peaks with alpha peaks, and the determination of several parameters (crystallographic structure, linear absorption, texture, temperature factors) before Rietveld application in order to avoid too many free parameters, this technique has proved to be a very powerful tool in applications in physical metallurgy.